Sometimes it's just a case of "bad timing" when aircraft has a need to divert.
I would suggest that a Friday evening/nighttime when plans by relevant handling agencies have been drawn up to have a certain amount of staff covering the expected flights with a lots of stands being occupied by aircraft having completed their flying duties for the day is likely to lead to a "no go" situation.
Have we soon forgotten about the TG 747, SQ A380 and AC A330 that all diverted in between 0700 and 0730 on 28th October? The relevant handling agencies I would imagine should still have a "normal" peak period shift on hand to cope with extra aircraft.
Other "smaller" airports, for want of a better phrase, may have the same number of staff on duty as MAN but as a result of perhaps having fewer aircraft on the ground or expected to arrive, could well be in a better position to handle extra flights.